fix(iap): address code review defects in freemium/IAP change

Fixes 9 of 10 review findings (10th requires a manual Play Console
step, no code change):

1. app.dart/banner_anuncio_superior.dart: move the top SafeArea inside
   BannerAnuncioSuperior so it only reserves status-bar height when an
   ad actually renders, restoring edge-to-edge layout for premium and
   free-unloaded users.
2. servicio_anuncios.dart: bound every interstitial await (load,
   presentation, and the injected implementation itself) with
   injectable timeouts so a callback that never fires can no longer
   hang a caller.
3. estado_entitlement.dart/hoja_premium.dart: expose a typed
   resultadoUsuario signal for purchase/restore failures and
   restore-found-nothing, with dedicated localized messages
   (compraError, restauracionSinCompras) across all 13 locales --
   never the raw developer/exception string.
4. main.dart/servicio_consentimiento.dart: add a GDPR/UMP consent flow
   (ConsentInformation/ConsentForm) that gates Mobile Ads SDK init on
   canRequestAds(); premium users never see a consent form; failures
   degrade to no ads instead of crashing or blocking startup.
6. servicio_anuncios.dart: track real ad presentation
   (onAdShowedFullScreenContent) so a failed-to-show interstitial no
   longer consumes a session cap slot.
7. banner_anuncio_superior.dart: add an explicit load-attempted guard
   so repeated didChangeDependencies (e.g. entitlement notifyListeners
   during a purchase) can only ever trigger one banner load attempt.
8. servicio_anuncios.dart: make esPremium a required constructor
   parameter, matching the hardened contract already applied to
   EstadoAlarmas/EstadoGrabacion/EstadoRadio.
9. hoja_premium.dart: add a dedicated premiumActivo localized string
   instead of reusing the equalizer's equalizerActive translation,
   across all 13 locales.

All fixes implemented RED-first (failing test before production
code). Full suite: 1261 passed, 2 pre-existing skips, 0 failures.
flutter analyze: 5 pre-existing issues only, 0 new.

[version set]

lib/l10n/app_ar.arb

@@ -901,5 +901,8 @@
   "funcionPremium": "ميزة مميزة",
   "limiteAlarmasAlcanzado": "لقد وصلت إلى الحد المجاني وهو 5 منبهات.",
   "desbloquearPremium": "فتح النسخة المميزة",
-  "restaurarCompras": "استعادة المشتريات"
+  "restaurarCompras": "استعادة المشتريات",
+  "compraError": "تعذّر إتمام عملية الشراء. حاول مرة أخرى.",
+  "restauracionSinCompras": "لم نجد أي عملية شراء سابقة في هذا الحساب.",
+  "premiumActivo": "النسخة المميزة مفعّلة"
 }